Software defined networking (SDN) comprises a plurality of hosts in communication over a physical network infrastructure, each host having one or more virtualized endpoints such as VMs or containers that are connected to one another over logical overlay networks that are decoupled from the underlying physical network infrastructure. One common characteristic of software defined networking is a separation of the control plane from the data plane. Control planes in a network are concerned with determining the logical overlay network topology and maintaining information about network entities such as logical switches, logical routers, and virtualized endpoints, etc. The logical topology information is translated by the control plane into state data, such as forwarding table entries to populate forwarding tables at the virtual switches at each host. In large data centers having hundreds or thousands of hosts and/or logical networks, the processing and communication requirements are such that a single computer system is incapable of performing all the necessary tasks for all the hosts and networks. To address this problem various techniques for scaling out the control plane have been implemented. For example, to distribute some of the processing load to the hosts, the control plane may be divided into a central control plane (CCP) as well as local control planes (LCP) at each host. The CCP may be implemented as a cluster of CCP nodes in order to further distribute the processing load. Typically, the CCP nodes directly transmit state data to the LCP on every host individually in order to ensure that all hosts maintain a unified picture of the system.
While it is generally effective for CCP nodes to transmit the state data to the LCP on each host directly, this process can become inefficient when the number of hosts scales (e.g., to thousands of hosts). Two-way communication between a relatively small number of CCP nodes and a vast number of LCPs can prove to be a source of latency, and can impose a significant burden on the communication resources of the CCP nodes. Consequently, the requirement of directly transmitting state data to each LCP directly can impose a practical limit on the number of hosts that the CCP is capable of supporting. Therefore, there exists a need for a more efficient method of distributing state data to a plurality of LCPs so that a CCP can support a larger number of hosts.